Data from: Heterogeneous rates of molecular evolution and diversification could explain the Triassic age estimate for angiosperms

Dating analyses based on molecular data imply that crown angiosperms existed in the Triassic, long before their undisputed appearance in the fossil record in the Early Cretaceous. Following a re-analysis of the age of angiosperms using updated sequences and fossil calibrations, we use a series of simulations to explore the possibility that the older age estimates are a consequence of (i) major shifts in the rate of sequence evolution near the base of the angiosperms and/or (ii) the representative taxon sampling strategy employed in such studies. We show that both of these factors do tend to yield substantially older age estimates. These analyses do not prove that younger age estimates based on the fossil record are correct, but they do suggest caution in accepting the older age estimates obtained using current relaxed-clock methods. Although we have focused here on the angiosperms, we suspect that these results will shed light on dating discrepancies in other major!

基于分子数据的年代学分析显示，冠群被子植物（crown angiosperms）的演化历史可追溯至三叠纪，远早于其在早白垩世化石记录中得到确凿证实的出现时间。本研究在采用更新后的序列数据与化石校准对被子植物起源年代开展重新分析后，通过一系列模拟实验，探究了偏老年代估计值的两种潜在成因：（i）被子植物基部支系附近发生的序列进化速率大幅转变，以及/或（ii）此类研究中采用的代表性类群采样策略。研究结果表明，上述两类因素均会显著导致年代估计值偏老。本分析并未证实基于化石记录的偏年轻年代估计值的正确性，但确实提示在采信当前基于松弛分子钟方法（relaxed-clock methods）得到的偏老年代估计值时应保持审慎态度。尽管本研究聚焦于被子植物类群，但我们推测这些结果将有助于阐明其他主要类群中的年代学分歧。